Businesses, industrial plants, nuclear and conventional power plants, warehouses, stores and similar places with records, equipment, fixtures, and inventory often need automated fire protection to suppress fire. CO2-type fire suppression systems are common, with suppressant gas discharge tanks stored on or adjacent the premises, connected by piping to discharge nozzles stationed around an enclosed area (room, wing, building) to be protected. A central detection and control panel monitors an array of fire/smoke/heat sensors located in the area being protected, and sends a discharge signal to discharge CO2 from the storage tanks when a fire is sensed. In the case of occupied environments, the discharge signal is delayed for a short period of time after a fire is sensed, for example with a programmed delay where the suppressant gas is stored in high pressure cylinders in or near the room, or with an inherent delay where the suppressant gas is stored in remote, low pressure bulk cylinders and takes time to reach the discharge nozzles. During the delay the room is cleared of people with an alarm such as a horn.
A simplified example of a CO2 type fire suppression system 10 is shown schematically in FIG. 1, in which a room 12 is provided with fire detectors 14 connected to a controller 16 to signal the start of a fire. Controller 16 can be any known type of controller, usually taking the form of (and referred to as) a control panel. Control panel 16 is connected in known manner at 17 to the control valving 18a for a bank of suppressant gas storage tanks 18, which may be any known type of high pressure cylinders or low volume bulk tanks or combinations thereof. Tanks 18 are connected by piping 20 to an array of discharge nozzles 22 located about the interior of room 12. When control panel 16 receives a signal from detectors 14 that a fire has started, the control panel sends a discharge signal to open discharge valving 18a, thereby releasing pressurized suppressant gas from tanks 18 into the room to suppress the fire by oxygen displacement. The suppressant gas may also provide an optional cooling effect, depending on the gas and the discharge valving. The typical discharge cycle carried out by control panel 16 is an initial discharge (for example one minute) in which the system should achieve a desired suppressant gas concentration level calculated to extinguish the fire, followed by a longer hold time (for example twenty minutes) during which the concentration should be maintained to make sure the fire is out and will not start again.
Fire suppression systems should be tested periodically to ensure that that they will function properly in a real fire. Beyond basic nozzle function, the ability of a system to reach and hold desired CO2 concentrations in the protected area is critical. Unfortunately, most such systems are not tested, or are inadequately tested, for a number of reasons.
The proper way to test an automated, large-area fire suppression system for reach-and-hold CO2 concentration ability is to carry out a full-discharge test. This involves shutting down the facility, bringing in specialists with portable discharge concentration monitors, clearing the facility of people, discharging the storage tanks of CO2, ventilating the facility, and going back in (often with self-contained breathing apparatus) to check the monitors. The facility owners are often reluctant to go through this procedure because of the downtime, specialist fees, and perceived cost of recharging the bulk storage tanks with CO2. Many fire suppression systems are accordingly never properly tested, the owners usually relying on theoretical specifications or limited nozzle function tests. To make matters worse, the system specifications are often marginally written to keep costs and CO2 storage space down, and the site-built nature of the systems often involves non-specialist contract labor not experienced with fire suppression and CO2 discharge issues.
If a fire does occur, it is also difficult to determine whether the suppression system actually worked, creating insurance issues. Insurance people are generally believed to have limited knowledge of CO2 type fire suppression, and of what makes for a proper system or a proper testing and maintenance program. The insurance people accordingly tend to rely on the marginal installer specifications, which can create problems both for the system's performance in a fire and in insurance evaluations afterward.